I2S 24 bit and 16 bit, the Signal to noise ratio was same

RE: I2S 24 bit and 16 bit, the Signal to noise ratio was same

haakonsh — Thu, 05 Aug 2021 08:33:43 GMT

Yeah I think so.

RE: I2S 24 bit and 16 bit, the Signal to noise ratio was same

OPQ — Wed, 04 Aug 2021 11:02:10 GMT

Hi haakonsh,

Thanks for reply.

config.format = NRF_I2S_FORMAT_I2S;
config.alignment = NRF_I2S_ALIGN_LEFT;

Do you mean these two configurations？

RE: I2S 24 bit and 16 bit, the Signal to noise ratio was same

haakonsh — Wed, 04 Aug 2021 10:53:40 GMT

[quote user=""]I debug and watch the easyDMA data of nrf_drv_i2s, and it seems that 4 bytes of data will be generated for each acquisition. Although the I2S 24-bit mode is used, I am not sure if there is a problem here?[/quote]

This is a feature of the I2S spec, a sign extension of 8 bits is added when used in 24-bit mode.
See Width, alignment and format, EasyDMA, and Memory mapping for 24 bit stereo. CONFIG.SWIDTH = 24Bit, CONFIG.CHANNELS = Stereo.

The I2S devices needs to have the same alignment configuration otherwise you'll probably loose 8 lsb/msb depending on config.